Newly released tapes recorded during Lyndon B. Johnson’s presidency have confirmed long-held rumors that in 1968, then-presidential candidate Richard M. Nixon worked to sabotage Vietnam War peace talks.

The LBJ tapes were recently declassified and released by the Johnson library in Austin, Texas. According to the BBC’s summary of the tapes, not only did Nixon possibly commit treason, but LBJ knew about it and decided not to expose him in the closing days of an election that Nixon barely won.

While Nixon became infamous for his tendency to record nearly every conversation during his presidency, which proved to be his undoing, he wasn’t the first commander in chief to document everything so thoroughly. In fact, Nixon seems to have gotten the idea to keep an extensive set of recordings from LBJ himself. John F. Kennedy also taped some of his meetings.

In the summer of 1968, the Paris peace talks were under way, working to find a diplomatic solution to the Vietnam War. While the talks seemed to be going well, by October, South Vietnam had dropped out, just as Johnson was about to negotiate an end to all bombings in North Vietnam. The Democratic nominee, Vice President Hubert H. Humphrey, belatedly called for a bombing halt, and closed the gap with Nixon in the final days.

The reason for the Saigon government's withdrawal? Richard Nixon had convinced the South Vietnamese delegates that they would get a better peace deal under his presidency. Nixon’s campaign relied heavily on the war continuing, and he saw an end to the bombings as an grave threat to his campaign.

And while Nixon sabotaged the talks, he publicly denied any knowledge or involvement in the South’s withdrawal, ultimately prolonging the war for five more years. His actions could have conceivably resulted in treason charges if Johnson had made the news public.

"We have found that our friend, the Republican nominee, our California friend, has been playing on the outskirts with our enemies and our friends both, he has been doing it through rather subterranean sources,” Johnson told Sen. Richard Russell, D-Ga., in one taped phone call. “Mrs. Chennault is warning the South Vietnamese not to get pulled into this Johnson move."

Anna Chan Chennault, the Chinese-born widow of World War II aviation legend Claire Chennault, was a Republican activist and Nixon's emissary to the South Vietnamese. She is still alive at age 87.

Why did Johnson refuse to break the news? In part, it would mean admitting that he had bugged several ambassadors’ phones, which also might not sit well with the American public. Johnson informed Humphrey of Nixon’s actions, though he ultimately decided not to make the announcement in the vain hope that he was on track to win anyway.

In the end, Nixon used Johnson’s “failure” to end the Vietnam War as a major selling point, even citing the South’s withdrawn from peace talks as a black mark against Johnson. Nixon won by an extremely small margin and once in office, escalated the war for years before negotiating for peace in 1973.

While the confirmation of Nixon’s behavior is shocking enough, the LBJ tapes also reveal that the Democratic president at one point had a secret plan to re-enter the 1968 presidential election at the last second. In the spring, after strong showings by the antiwar candidates Eugene McCarthy and Robert F. Kennedy, Johnson abruptly announced that he would not run for a second term, and Humphrey entered the race in his place.

However, Johnson began to doubt his decision and secretly decided to make a surprise appearance at the Democratic Convention in Chicago, which had decended into a series of increasingly violent protests and riots. Ultimately, Johnson backed out of the plan due to the Secret Service’s concerns for his safety at the convention. As a result, Humphrey became the Democratic candidate and Nixon became president.